Sympathetic ink



Patented Sept. 15, 1925.

UNITED s'r ra ALLEN ROGERS PATENTTOFYFICE.

,oF BROOKLYN, NEwYoax, ASSIIGNOR T MIMO CORPORATION," or

NEW YORK, N. Y., A CORPORATION or DELAWARE SYMPATHETIC INK.

No Drawing.

To all whom it may concern:

' Be it known that I, ALLEN ROGERS, a citizen of the United States,residing atjBrooklyn, in the county of Kings and State of New York, haveinvented certain new andv useful Improvements in Sympathetic Inks, ofwhich the following is a specification.

This invention relates to invisible or sympathetic inks-and processes ofmaking the 1 same, and comprises an ink for printing on newspaper andthe like with-the usual forms of printing machines, consisting of asufliciently thick vehicle to allow proper. spread on the type andcarrying in solution-0r sus- I 1 pension a substance which whenafterwards properly treated on the a visible effect.

Many sympathetic inks are known which can be applied in water solutionor even in paper will produce alcohol, but these inks will either effectthe gelatin rolls of the printing machine or will not have suflicientbody to spread uniformly on the type.

' As it is impossible to use oil in making up '1 a sympathetic ink,owing to the stain pro-' duced, some other medium had to be found whichwould carry the activesubstance and meet all. of the other requirements.Although many substances when applied to I 0 paper are invisible and maybe developed by subsequent treatment I have found that the best one forthis purpose is the chemical known as phenolphthalein and in thedescription to follow this substance will be used. I have found,however, that cobalt chloride, ferrous ammonium sulphate, ferroussulphate, sugar and several other sub-' stances give more or lesssatisfactory results. In making up this ink I dissolvethe phe 40nolphthalein in alcohol and to obviate any risk from fire I add acertain amount of carbon tetrachloride. Other non-inflammable substancescan also be used, but on account of the cost I prefer the carbontetrachloride. The solution when prepared as above may be used forprinting, but owin to rapid evaporation does not givesatis actoryresults. Thisdiflicuty may be offset'by dissolvingin the mixture acertain amount of waterwhite rosin and chip soap the proportions ofwhich will be given later. This thickening mixture, however, can only beused with organic substances and is not aption it does not mixreadily'and so it be- Application filed September 20, 1923. Serial No.663,901.

'plicable when cobalt or other metallic salts are used; To cover allcases I find that the most satisfactory thickening :agent is glycerine,and byits use any degree of thickness may be secured. -When glycerine isadded to the alcohol and carbon tetrachloride solu-"' comes necessary toadd some other substance which will produce a uniform product. I havefound that byadding a small quantity of acetone the glycerinewill thendissolve readilyand .the resulting solution is uniform. Acetone initself is inflammable, but the presence of the carbon tetrachloride willovercome the fire hazard.

Although various proportions of the compounds maybe mixed to produce asympathetic ink I have found the following to give the best results:phenolphthalein 1 part, alcohol 3 parts, carbon tetrachloride 2 parts,acetone 3 parts, glycerine 16 parts. This ink may be developed by analkali applied on a cloth to the surface of the paper, e. g. asolutionof washing soda and water Having thus full described my saidinvention,'what I claim as new "and desire to secure by Letters Patent,is.

1. A sympathetic ink comprising alcohol phenolphthalein, carbontetrachloride, a glycerine, substantiall as set forth.

2. A sym athetic ink comprising. three parts alcoho one partphenolphthalein, two parts of carbon tetrachloride, and sixteen' partsof glycerine, substantially as set forth.

3. A sympathetic'ink comprising alcohol, phenolphthalein, carbon.tetrachloride, glycerine, and a solution-promoting agent,'substantiallyas set forth. 4

4. A sympathetic ink comprisin alcohol, phenolphthalein, carbontetrachlor de, glycerine, and acetone, substantially as setforth.

5. A sympathetic ink comprising three 5 parts alcohol, one parthenolphthalein, two partso-f carbon tetrach oride, sixteen partsglycerine, and three parts of, acetone, ,substantially as set forth.

6. A process for -making a sympatheticumo ink which consists indissolving phenol? phthalein in a mixture of alcohol, carbontetrachloride and acetone and to this mixture adding enough glycerine togive the de- I iireclll body for printing, substantially .as set me ort7. A s mpathetio ink comprising glycersolution-promoting agent,substantially as ine, alco 01, an anti-combustion in dient set forth.and arm-ingredient normally invisib e when V In witness whereof, Ihavehereunto set 1! applied to paper, substantially as set forth. my handand seal at Brooklyn, New York, 5 8. A sympathetic ink comprising achemithis 18th day of September, A. D. nineteen cal normally invisiblewhen applied to paper, hundred and twenpfiy-three.

a volatile, solvent therefor, glycerine', and a: ALL N ROGERS. [L s.]

